Communication system



C.- 30, 1945- T. w. w. HOLDEN COMMUNICATION SYSTEM Filed Aug. 19, 1942 2 Sheets-Sheet l Ma/Maher@ J 6@ f/T/ Fry/75 30, i945 T. w. vnu-HOLDEN y 2,387,906

COMMUNICATION SYSTEM Filed Aug. 19, 1942 2 Sheets-Sheet .-2

IN V EN TOR.

.50o @des Patented Oct 30, 1945 iii 2,387,906 COMMUNICATION SYSTEM Thomas W.

Ind.,

11 Claims.

` communication system.

The communication system of this invention may be used to overcome fading or atmospheric nels than heretofore available.

It is, accordingly, an object of the invention to provide a communication system,

Figure 1 diagrammatically shows one form of embodying the invention; elevation of a frequency divider forming part of the transmitting apparatus;

Figure 3 is a view in generally vertical section W. Holden, Fort to The Magnavox Comp a corporation of In Application August 19, 1942,

any, Ltd., diana Wayne, Ind., assigner Fort Wayne,

Serial N0. 455,296

in generally line 4 4 of typically spoken Word.

All tones or sounds consist of a repetition of Wave trains of a definite pattern, as illustrated in Figure '7 in respect to the word farmers Since, therefore, as can Figure 7, any tone,

nine-tenths of each ceiving station by'reconstruction from the characteristic Wave patterns.

As indicated in system embodying this invention may comprise a microphone 2 from which the audio-or voice frequency carrier and feeds the modulated radio frequency signal to the transmitter l0 feeding the transmitting antenna l2. The radio frequency signals received by the receiving antenna I4 are fed to radio receiver E6 which, in turn, supplies the rectified signals or message portions to a frequency multiplier I8 by means of station, communication This system cuits, as Well wireless. It

can be used with telephone ciras radio circuits, either Wired or will be evident, of course, that ii -recording tape sed with telephone circuits, suitable terminal pparatus will be fed from the frequency di- Lder 6 at the transmitting end and appropriate arminal apparatus will be used at the receiving nd to feed the frequency multiplier |8.

The frequency divider vor reducer 6 at the ransmitting station divides or reduces the voice be changed to characteristics of the transmisfrequency multiplier I8 at the reconstructs the form and freiion system. receiving station restores or speech or signal to its original quency. The frequency divider or reducer 6 comprises, as best shown in Figures 2 to 5, a synchronous motor 20 supported on a suitable base or standard 22 and driving rubber wheels or pulleys 24 and 28. The wheel 24 drives a disc 28 rlxed to a rotary shaft 30 suitably supported and journaled in posts 32 upstanding from the base or standard 22. The rubber wheel 26 engages the annular flange 34 of a drum 36 to the periphery of which there is secured the usual magnetic 38. A recording coil or head 48 is disposed in radial juxtaposition to the tape 38 and applies'the message to this tape. This coil is fed by the amplifier 4, as indicated in Figure l. The drum 35 is mounted loosely on the shaft relative thereto, but held againstJ the collars 42. A disc 44 shaft and positioned within the cylinder formed by the recording tape 38.

The disc 44 carries take-off or pick-up coils 46, 48 and 50. Each pick-up coil is mounted on the disc for angular movement relative thereto in a direction substantially radially of the disc. The mounting means may comprise a mounting plate 52 to one end of which the coil is fastened, the other end of the plate being pivoted to the disc 44 as by a stud or bolt 54. A spring strip 56 is secured at one end, as by block 58, to the disc 44 above the plate 52 and at its other free end bears against the upper side edge of the plate v52 so as to normally urge this plate away from the recording tape 38. Movement of the plate inwardly of the disc may be limited by a stop pin 60, or the' like, secured to the disc on the opposite side of the plate 52. Each pick-up'is short circuited when it is out of engagement with the recording tape. This may be accomplished by connecting the leads 62 and 64 to each pickup to a shunting switch 66. The switch 66 may comprise a resilient contact blade 68 fixed at one end to a terminal block 'l0 fastened to the disc above the plate 52, and an adjustable contact screw 12 threaded into a block 14 fastened to the disc. Any suitable means may be used to mount the contact blade and screw on the disc 44. The blade 68 is so positioned that at its free end it engages the upper side edge of the plate 52 so that as the plate moves radially inwardly of the disc the blade 68 engages the contact screw 12 and completes the shunting or pick-up magnet 46. The pick-up coils are moved radially outwardly in sucession to engage successively the recording tape 38 with which they are held in engagement for 'a predetermined interval by a stationary cam bar 16 concentric to the disc and drum and formed at its upper free end with a cam surface 18 which, on being engaged by a cam lug 80 depending from the lower edge of the plate 52, moves the pick-up coil or magnet into engageemnt with the recording tape 38. The bar 16 may be formed integrally with a bar 82 extending upwardly from the circuit around the coil` coil fed by the receiver base or platform 22 and formed with an yoffset arm 84 permitting the bar 16 to be positioned in close juxtaposition to the outer face of the disc 44. The bar 16 is preferably of such arcuate extent as to permit one pick-up unit to be moved by its spring out of operative relation with the tape at the same instant as the next following pick-up unit is moved by the bar into operative relation with the recording tape. The several pick-up coils 46, 48 and 50 are connected in Series by their respective leads B2 and 64 and to slip rings 88 and 88 with which cooperate brushes 90 and 92 connected by leads 94 to the modulator 8.

The diameters of the wheels 24 and 26 and of the disc 28 and the annular flange 34 of the drum 36 are so proportioned that the pick-ups rotate at a speed less than the peripheral speed of the tape 38. Preferably the pick-ups are made to rotate at a speed which is nine-tenths of the peripheral speed of the recording tape.

` recorded on the recording tape'38 may be wiped therefroinor extinguished as by means of the conventional wiper or extinguishing electro-magnet 96 suitably energized, as byA battery 98, the electro-magnet 96 being positioned also in radial juxtaposition to the recording tape and preferably in diametrically opposed relation to the recording coil or magnet 40.

The frequency multiplier I8 is preferably of substantially the same structure as the frequency divider 6 and differs therefrom only in that the driving motor |00 (Figure 6) drives the disc|02, which carries three pick-up coils |04, at a speed which is a multiple of the speed at which it drives the drum '|06' carrying the recording tape |08 and drives the pick-ups and tapes in opposite directions. The motor |00 drives the disc |02 through the rubber wheel H0, the disc V| |2 and the shaft |I4, and drives the drum |06` through the smaller rubber wheel IIB which directly engages an annular flange ||8Y of the recording drum. The signals or message Wave patterns are recorded on the tape |08 by a suitable recording I6 and the reconstructed signals are fed from the pick-up coils |04 through leads and slip rings, connected in the same maniiir as illustrated in Figures 2 and 3, to the phones By rotating the disc V44 carrying pick-ups 46 at a speed which is less than the peripheral speed of the recording tape 38, the frequency of lthe signal currents recorded on the tape is, in effect, reduced. If thefrequency alone were reduced, then a greater time would be required to send out the full message.

Analysis of vibration forms of words, tones, syllabic wave trains, etc., shows that each word, tone, or syllabic wave train is comprised of one or more sets of repeated wave forms in continuous sequence. Any one wave form of each such set will, therefore, be characteristic of the entire train of identical wave forms, and if each wave form be reduced in frequency, the whole of the wave train may be reconstructed, as far as intelligiblity is concerned,by repeating that same wave form at a higher frequency, equal of course to the Original frequency of the wave form.

Thus in the present invention only a fraction of the repeated wave patterns is sent .out, and the remainder of each wave pattern is supplied at the receiving station by the frequency multiplier which speeds up the frequency by the same amount as it is slowed down by the frequency divider. If, as in the preferred form, thefrequency of the signals or messages recorded on the tape is reduced to ten percent of the original recorded frequency, by driving the pick-up magnets S to 50 ata speed which is nine-tenths of the peripheral speed of the recording tape, then "7 a speed which is nine times the peripheral speed of the recording tape |08. It will be evident that other speed relations between the pick-up Vmagnets 4B to 48 and the recording tape 38 may be employed, and that the message will be reconstructed into intelligible form only at a receiving station at which'the pick-up magnets rotate proportionately faster than the recording tape |08.

Since the transmitted carrier is modulated at frequencies which are one-tenth of normal, more transmitting channels may be made available without interference one with the other, and the receivers may be made more sharply selective; in

other words, tuned more precisely to the carrier frequency. Fading and static interference will correspondingly be reduced.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. The method of transmitting intelligence which comprises subdividing the voice currents to be transmitted into syllabic sections, eliminating repetitions portions of each syllabic section and transmitting the balance at reduced frequency to a distant station, at the distant station increasing the frequency of each syllabic section to its original value and repeating each syllabic section at the increased frequency to reconstitute each syllable of the original voice currents at the transmitting station.

2. The method of transmitting intelligence secretly from a true record wave form of the message to be transmitted which comprises picking up from the record Wave form selected portions only at a speed fixed, for at least each transmission, and lower than the speed at which it was originally recorded to reduce the frequencies of the selected portions, transmitting said selected portions at said reduced frequencies to a distant station, and there repeating each selected portion a suflicient number of times at the original frequency at which the message was recorded to restore the message to its original record Wave form.

3. The method of transmitting intelligence Which comprises making a true record Wave form of the message at a definite speed, picking up from the record characterizing portions only of the recorded message wave form at a speed below, and in predetermined ratio to, the speed at which the message was recorded to reduce the frequencies of the picked up characterizing portions, transmitting the characterizing portions at the reduced frequency to a distant station, recording the characterizing portions as transmitted to the distant stations, at a denite speed, and repeatedly picking up each characterizing portion from the last recording at a speed sufficiently 'ing sections at the reduced frequency to Va distant station and there repeating each syllable characterizing section a suicient number of times at its original frequency to reform the sections into a reproduction of a complete message.

5. A system for transmitting messages which comprises means for making a true record of the message to be transmitted, means for picking up from the record at least one characteristic portion of each Wave train composing the message wave form at a speed such that the pick-up time for the portion of each Wave train is substantially the same as the recording time for the entire `wave train characterized thereby, whereby repetitious portions of each Wave train composing the message wave form are eliminated and the balance picked up at a frequency so reduced that the pick-up of the message is continuous' where the recorded message is continuous and discontinuous wherethe recorded message is discontinuous, lmeans for transmitting said characteristic portions at the reduced frequency to a distant station, means at the distant station for recording said characteristic portions, as transmitted, at the reduced frequency and pick-up means at said distant station for repeatedly picking up each of the said characteristic portions from said last record at a speed sufficiently higher than the speed of the last recording to reconstitute each Wave train from its characteristic portion and reproduce the message at its original wave form and frequency composition.

5. In an apparatus receiving unintelligible message characterizing wave sections transmitted at reduced frequencies, a traveling recording tape driven at a preselected speed, means for recording on said tape said messa-ge characterizing sections at the reduced frequency of transmission, a plurality of traveling pick-ups, means driving said pick-ups at a speed higher than the speed of the tape in the predetermined ratio of the original message frequencies to the reduced trans-- mitted message frequencies, and means rendering said pick-ups successively effective in timed relation to pick up repeatedly each message characterizing section to reconstitute from the characterizing sections of reduced frequency the original message in its wave form and frequency composition.

7. In an apparatus for receiving unintelligible, uninterrupted syllable characterizing wave cycles of a message transmitted at reduced frequencies, a traveling recording tape driven at a preselected speed, means for recording on said tape said uninterrupted syllable characterizing Wave cycles at the reduced frequencies of transmission, and traveling pick-up means traveling at a speed higher than the speed of the tape in the ratio of the original message frequencies to the reduced transmitted message frequencies and constructed and arranged to repeatedly pick up each uninterrupted syllable characterizing Wave cycle to intelligibly reproduce each syllable of the original message at its original frequencies.

8. In an apparatus receiving unintelligible, uninterrupted message characterizing sections transmitted at reduced frequencies, an endless recording tape driven continuously at a preselected speed, means for recording on said tape said message characterizing sections at the reduced frequencies of transmission, means for blotting out said recorded message sections, and traveling pick-up means traveling at a speed higher than the speed of the tape in the ratio of the original message frequencies to the reduced transmitted message frequencies, said recording means and said blotting out means being spaced longitudinally of the path of said -tape to permit said pick-up means repeatedly to pick up each characterizing message section between the time of its recording and the time of its blotting out whereby to reconstitute from each characteristic section the true message section characterized thereby.

9. In apparatus for transmitting messages, a rotary member carrying an endless recording tape and driven continuously at a preselected speed, means for forming on said tape, as it is driven, a true record of the message, a plurality of pick-ups, a common rotary carrier for said pick-ups, means driving said carrier at a speed such that the speed of the pick-ups is proportional to, but less than, the speed of the recording tape, means for rendering said pick-ups effective successively in timed relation whereby they pick up characteristic sections only of the syllabic wave trains composing the recorded message and eectively eliminate repetitious portions of each such syllabic wave train, the speed of driving of the pick-ups being so proportioned to the speed of the tape that the pick up time for each said characteristic section is substantially the same as the recording time for the entire syllabic wave train characterized thereby, and means, fed by said pick-ups, transmitting said syllabic characterizing sections to a distant station.

10. In apparatus for transmitting messages, a rotatable member, a recording tape mounted on said member for rotation therewith, a stationary recorder for recording each message on the tape as the tape is rotated, a second rotatable member, a plurality of pick-ups carried by said second rotatable member and operatively associated with said tape for picking up sections of a message recorded on said tape, driving means .for said rotatable member constructed and arranged to rotate the tape and pick-ups relatively at a predetermined speed lower than the speed of the tape, means for rendering said pick-ups successively effective to pickupsections of the recorded message from the tape, the speed of rotation of they pick-ups relative to the tape and themovement of the pick-ups being predetermined to cause the pick-ups to pick up con--v tinuously at reduced frequencies only uninterrupted characterizing wave signal patterns of each syllable wave train composing the message and thereby eliminate repetitions portions of each said syllable wave train.

11. In apparatus receiving unintelligible syllable characterizing, uninterrupted wave signal patterns of a message transmitted at reduced frequencies, a rotatable member, an endless recording tape mounted on said member for rotation therewith, stationary means for recording on said tape said syllable characterizing wave patterns at the reduced frequency of transmission, a second rotatable member, a plurality of pick-ups carried by saidsecond rotatable member and operatively associated with said tape for picking up the wave recorded on said tape, driving means for said rotatable members constructed and arranged to move the tape and pick-ups relatively at a predetermined higher speed than the speed at which the wave patterns were recorded on the tape, means for rendering said pick-ups successively eiective to pick up the recorded wave patterns from said tape, the speed of rotation of the pick-ups relative to the tape and the number of pick-ups being predetermined to cause the pick-ups to repeatedly pick up at the original message frequency each syl lable characterizing wave pattern whereby to reform from each such pattern the syllable characterized thereby.

THOMAS W. W. HOLDEN. 

